Photoinduced Addition of Phthalimide to Unactivated Alkynes†

Abstract

Photoexcited phthalimide in equilibrium with its conjugated base produces the regioselective hydrophthalimidation of conjugated alkynes. The vinylphthalimide thus obtained is hydrolyzed to the corresponding carbonyl compound. With unconjugated alkynes, the outcome is a double addition of phthalimide to the triple bond. The reaction is assumed to take place via single electron transfer from either the alkyne or the phthalimide anion to the excited phthalimide as the primary photoprocess.

Novel N-Hydroxymethylation of Phthalimide by Titanium Dioxide Photocatalyst in Methanol

“…A literature survey of existing photochemical reactions of phthalimides without TiO 2 indicates that irradiation of phthalimide 1 with UV light gave several kinds of photoreduction products such as 3-hydroxyphthalimidine 2, its dimer 3, and C-hydroxymethyl-3-hydroxyphthalimidine 4 depending on the reaction conditions. [9][10][11][12][13] Similarly, upon irradiation of 1 in methanol gave 2 in low yield. Meanwhile, irradiation of phthalimide 1 in methanol (40 mL) in the presence of NaOH (1.5 M) reported the production of 3 and 4 in moderate yields, 35% and 40% yields, respectively.…”